A WEALTHY 72-year-old businessman who owned restaurants in New York twisted generosity into a nightmare for a woman he took in after Hurricane Sandy, a lawsuit claimed.

Francesca Riccardi, 33, a horse trainer and single mum, alleged that Frank Villano served her drugs Ambien and Xanax with oatmeal nightly in his Long Island mansion, then undressed and touched her in her sleep while her 10-year-old son was in the same bed and witnessed the abuse.

Villano, a divorced father of four, was "obsessed" with Riccardi and warned that if she moved out, he would make her life "a living hell," according to the suit filed in Queens Supreme Court.

"He was a very rich man and wanted to take care of them for the rest of their lives," Riccardi said Villano told her and her son.

Villano, given a Distinguished Alumni Award by Long Island University in 2007, founded several businesses, including a software company that served Fortune 100 clients. In 2005, he donated $1 million to a Greenwich Village child-protection centre.

"He acted like a father figure," said Riccardi's lawyer, Joseph Tacopina. "This was despicable conduct by a guy who knew Francesca was traumatised by Hurricane Sandy and took advantage of her."

Riccardi, whose mother was a friend of Villano, accepted his offer to let her and her son stay in his $US3 million home in November 2012. She had lost all her belongings when Sandy flooded the Staten Island home she had been living in with her boyfriend. When a friend died in a car crash, she became "an emotional wreck", she said.

Villano tried to monitor and control her every move, Riccardi said.

He installed a GPS locating device on a car he loaned her, sent her 930 texts, phoned incessantly, hired a private eye to tail her, and stole her AOL password to pose as her and cut ties with her ex-boyfriend, telling him Villano wanted to marry her, the suit alleged.

"You belong to me and nobody else," she said Villano told her.

Villano gave Riccardi his own sleeping and anti-anxiety pills nightly, the suit said.

"Villano would enter their room, disrobe Riccardi in her sleep, and put his hands on her body. Villano would even kiss her face and moan while he was molesting her. All this was done in front of [Riccardi's son] and [he] witnessed it," the suit said.

The boy told her of the abuse, she said. On January 2, 2013, she didn't take the pills.

Villano came into her room at 2am and sexually assaulted her, she claimed, adding that she screamed and pushed him off.

She moved out and filed complaints with the police. He was not arrested or charged.

Villano's lawyer, Aida Leisenring, called Riccardi a "gold digger".

"It's a ridiculous complaint and a complete lie," Leisenring said. "It's transparent that she wants money."

In court papers, Villano says they had "consensual sexual contact".

Riccardi, who moved to a Queens apartment with her son, seeks unspecified compensation and punitive damages.